Inbred maize line PH42B

ABSTRACT

An inbred maize line, designated PH42B, the plants and seeds of inbred maize line PH42B, methods for producing a maize plant produced by crossing the inbred line PH42B with itself or with another maize plant, and hybrid maize seeds and plants produced by crossing the inbred line PH42B with another maize line or plant.

FIELD OF THE INVENTION

This invention is in the field of maize breeding, specifically relatingto an inbred maize line designated PH42B.

BACKGROUND OF THE INVENTION

The goal of plant breeding is to combine in a single variety or hybridvarious desirable traits. For field crops, these traits may includeresistance to diseases and insects, tolerance to heat and drought,reducing the time to crop maturity, greater yield, and better agronomicquality. With mechanical harvesting of many crops, uniformity of plantcharacteristics such as germination and stand establishment, growthrate, maturity, and plant and ear height, is important.

Field crops are bred through techniques that take advantage of theplant's method of pollination. A plant is self-pollinated if pollen fromone flower is transferred to the same or another flower of the sameplant. A plant is cross-pollinated if the pollen comes from a flower ona different plant.

Plants that have been self-pollinated and selected for type for manygenerations become homozygous at almost all gene loci and produce auniform population of true breeding progeny. A cross between twodifferent homozygous lines produces a uniform population of hybridplants that may be heterozygous for many gene loci. A cross of twoplants each heterozygous at a number of gene loci will produce apopulation of hybrid plants that differ genetically and will not beuniform.

Maize (zea mays L.), often referred to as corn in the United States, canbe bred by both self-pollination and cross-pollination techniques. Maizehas separate male and female flowers on the same plant, located on thetassel and the ear, respectively. Natural pollination occurs in maizewhen wind blows pollen from the tassels to the silks that protrude fromthe tops of the ears.

A reliable method of controlling male fertility in plants offers theopportunity for improved plant breeding. This is especially true fordevelopment of maize hybrids, which relies upon some sort of malesterility system. There are several options for controlling malefertility available to breeders, such as: manual or mechanicalemasculation (or detasseling), cytoplasmic male sterility, genetic malesterility, gametocides and the like.

Hybrid maize seed is typically produced by a male sterility systemincorporating manual or mechanical detasseling. Alternate strips of twoinbred varieties of maize are planted in a field, and the pollen-bearingtassels are removed from one of the inbreds (female). Providing thatthere is sufficient isolation from sources of foreign maize pollen, theears of the detasseled inbred will be fertilized only from the otherinbred (male), and the resulting seed is therefore hybrid and will formhybrid plants.

The laborious, and occasionally unreliable, detasseling process can beavoided by using cytoplasmic male-sterile (CMS) inbreds. Plants of a CMSinbred are male sterile as a result of factors resulting from thecytoplasmic, as opposed to the nuclear, genome. Thus, thischaracteristic is inherited exclusively through the female parent inmaize plants, since only the female provides cytoplasm to the fertilizedseed. CMS plants are fertilized with pollen from another inbred that isnot male-sterile. Pollen from the second inbred may or may notcontribute genes that make the hybrid plants male-fertile. Usually seedfrom detasseled fertile maize and CMS produced seed of the same hybridare blended to insure that adequate pollen loads are available forfertilization when the hybrid plants are grown.

There are several methods of conferring genetic male sterilityavailable, such as multiple mutant genes at separate locations withinthe genome that confer male sterility, as disclosed in U.S. Pat. Nos.4,654,465 and 4,727,219 to Brat et al. and chromosomal translocations asdescribed by Patterson in U.S. Pat. Nos. 3,861,709 and 3,710,511. Theseand all patents referred to are incorporated by reference. In additionto these methods, Albertsen et al., of Pioneer Hi-Bred, U.S. patentapplication Ser. No. 07/848,433, have developed a system of nuclear malesterility which includes: identifying a gene which is critical to malefertility; silencing this native gene which is critical to malefertility; removing the native promoter from the essential malefertility gene and replacing it with an inducible promoter; insertingthis genetically engineered gene back into the plant; and thus creatinga plant that is male sterile because the inducible promoter is not "on"resulting in the male fertility gene not being transcribed. Fertility isrestored by inducing, or turning "on", the promoter, which in turnallows the gene that confers male fertility to be transcribed.

There are many other methods of conferring genetic male sterility in theart, each with its own benefits and drawbacks. These methods use avariety of approaches such as delivering into the plant a gene encodinga cytotoxic substance associated with a male tissue specific promoter oran antisense system in which a gene critical to fertility is identifiedand an antisense to that gene is inserted in the plant (see:Fabinjanski, et al. EPO 89/3010153.8 publication no. 329,308 and PCTapplication PCT/CA90/00037 published as WO 90/08828).

Another system useful in controlling male sterility makes use ofgametocides. Gametocides are not a genetic system, but rather a topicalapplication of chemicals. These chemicals affect cells that are criticalto male fertility. The application of these chemicals affects fertilityin the plants only for the growing season in which the gametocide isapplied (see Carlson, Glenn R., U.S. Pat. No.: 4,936,904). Applicationof the gametocide, timing of the application and genotype specificityoften limit the usefulness of the approach.

The use of male sterile inbreds is but one factor in the production ofmaize hybrids. The development of maize hybrids requires, in general,the development of homozygous inbred lines, the crossing of these lines,and the evaluation of the crosses. Pedigree breeding and recurrentselection breeding methods are used to develop inbred lines frombreeding populations. Breeding programs combine the genetic backgroundsfrom two or more inbred lines or various other broad-based sources intobreeding pools from which new inbred lines are developed by selfing andselection of desired phenotypes. The new inbreds are crossed with otherinbred lines and the hybrids from these crosses are evaluated todetermine which of those have commercial potential.

Pedigree breeding starts with the crossing of two genotypes, each ofwhich may have one or more desirable characteristics that is lacking inthe other or which complements the other. If the two original parents donot provide all the desired characteristics, other sources can beincluded in the breeding population. In the pedigree method, superiorplants are selfed and selected in successive generations. In thesucceeding generations the heterozygous condition gives way tohomogeneous lines as a result of self-pollination and selection.Typically in the pedigree method of breeding five or more generations ofselfing and selection is practiced: F₁ →F₂ ; F₃ →F₄ ; F₄ →F₅, etc.

Recurrent selection breeding, backcrossing for example, can be used toimprove an inbred line. Backcrossing can be used to transfer a specificdesirable trait from one inbred or source to an inbred that lacks thattrait. This can be accomplished, for example, by first crossing asuperior inbred (recurrent parent) to a donor inbred (non-recurrentparent), that carries the appropriate gene(s) for the trait in question.The progeny of this cross is then mated back to the superior recurrentparent followed by selection in the resultant progeny for the desiredtrait to be transferred from the non-recurrent parent. After five ormore backcross generations with selection for the desired trait, theprogeny will be heterozygous for loci controlling the characteristicbeing transferred, but will be like the superior parent for most oralmost all other genes. The last backcross generation is then selfed togive pure breeding progeny for the gene(s) being transferred.

A single cross hybrid maize variety is the cross of two inbred lines,each of which has a genotype that complements the genotype of the-other.The hybrid progeny of the first generation is designated F₁. In thedevelopment of hybrids only the F₁ hybrid plants are sought. PreferredF₁ hybrids are more vigorous than their inbred parents. This hybridvigor, or heterosis, can be manifested in many polygenic traits,including increased vegetative growth and increased yield.

The development of a hybrid maize variety involves three steps: (1) theselection of plants from various germplasm pools for initial breedingcrosses; (2) the selfing of the selected plants from the breedingcrosses for several generations to produce a series of inbred lines,which, although different from each other, breed true and are highlyuniform; and (3) crossing the selected inbred lines with differentinbred lines to produce the hybrid progeny (F₁). During the inbreedingprocess in maize, the vigor of the lines decreases. Vigor is restoredwhen two different inbred lines are crossed to produce the hybridprogeny (F₁). An important consequence of the homozygosity andhomogeneity of the inbred lines is that the hybrid between a definedpair of inbreds will always be the same. Once the inbreds that give asuperior hybrid have been identified, the hybrid seed can be reproducedindefinitely as long as the homogeneity of the inbred parents ismaintained.

A single cross hybrid is produced when two inbred lines are crossed toproduce the F₁ progeny. A double cross hybrid is produced from fourinbred lines crossed in pairs (A×B and C×D) and then the two F₁ hybridsare crossed again (A×B)×(C×D). Much of the hybrid vigor exhibited by F₁hybrids is lost in the next generation (F₂). Consequently, seed fromhybrid varieties is not used for planting stock.

Maize is an important and valuable field crop. Thus, a continuing goalof plant breeders is to develop high-yielding maize hybrids that areagronomically sound based on stable inbred lines. The reasons for thisgoal are obvious: to maximize the amount of grain produced with theinputs used and minimize susceptibility of the crop to environmentalstresses. To accomplish this goal, the maize breeder must select anddevelop superior inbred parental lines for producing hybrids. Thisrequires identification and selection of genetically unique individualsthat occur in a segregating population. The segregating population isthe result of a combination of crossover events plus the independentassortment of specific combinations of alleles at many gene loci thatresults in specific genotypes. Based on the number of segregating genes,the frequency of occurrence of an individual with a specific genotype isless than 1 in 10,000. Thus, even if the entire genotype of the parentshas been characterized and the desired genotype is known, only a few ifany individuals having the desired genotype may be found in a large F₂or S₀ population. Typically, however, the genotype of neither theparents nor the desired genotype is known in any detail.

In addition to the preceding problem, it is not known how the genotypewill react with the environment. This genotype by environmentinteraction is an important, yet unpredictable, factor in plantbreeding. A breeder of ordinary skill in the art cannot predict thegenotype, how that genotype will interact with various environments orthe resulting phenotypes of the developing lines, except perhaps in avery broad and general fashion. A breeder of ordinary skill in the artwould also be unable to recreate the same line twice from the very sameoriginal parents as the breeder is unable to direct how the genomescombine or how they will interact with the environmental conditions.This unpredictability results in the expenditure of large amounts ofresearch resources in the development of a superior new maize inbredline.

Pioneer research station staff propose about 400 to 500 new inbreds eachyear from over 2,000,000 pollinations. Of those proposed new inbreds,less than 50 and more commonly less than 30 are actually selected forcommercial use.

SUMMARY OF THE INVENTION

According to the invention, there is provided a novel inbred maize line,designated PH42B. This invention thus relates to the seeds of inbredmaize line PH42B, to the plants of inbred maize line PH42B, and tomethods for producing a maize plant produced by crossing the inbred linePH42B with itself or another maize line. This invention further relatesto hybrid maize seeds and plants produced by crossing the inbred linePH42B with another maize line.

DEFINITIONS

In the description and examples that follow, a number of terms are usedherein. In order to provide a clear and consistent understanding of thespecification and claims, including the scope to be given such terms,the following definitions are provided. NOTE: ABS is in absolute termsand % MN is percent of the mean for the experiments in which the inbredor hybrid was grown. These designators will follow the descriptors todenote how the values are to be interpreted. Below are the descriptorsused in the data tables included herein.

ANT ROT=ANTHRACNOSE STALK ROT (Colletotrichum graminicola). A 1 to 9visual rating indicating the resistance to Anthracnose Stalk Rot. Ahigher score indicates a higher resistance.

BAR PLT=BARREN PLANTS. The percent of plants per plot that were notbarren (lack ears).

BRT STK=BRITTLE STALKS. This is a measure of the stalk breakage near thetime of pollination, and is an indication of whether a hybrid or inbredwould snap or break near the time of flowering under severe winds. Dataare presented as percentage of plants that did not snap.

BU ACR=YIELD (BUSHELS/ACRE). Yield of the grain at harvest in bushelsper acre adjusted to 15.5% moisture.

CLN=CORN LETHAL NECROSIS. Synergistic interaction of maize chloroticmottle virus (MCMV) in combination with either maize dwarf mosaic virus(MDMV-A or MDMV-B) or wheat streak mosaic virus (WSMV). A 1 to 9 visualrating indicating the resistance to Corn Lethal Necrosis. A higher scoreindicates a higher resistance.

COM RST=COMMON RUST (Puccinia sorghi). A 1 to 9 visual rating indicatingthe resistance to Common Rust. A higher score indicates a higherresistance.

DID=DRYDOWN. This represents the relative rate at which a hybrid willreach acceptable harvest moisture compared to other hybrids on a 1-9rating scale. A high score indicates a hybrid that dries relatively fastwhile a low score indicates a hybrid that dries slowly.

DIP ERS=DIPLODIA EAR MOLD SCORES (Diplodia maydis and Diplodiamacrospora). A 1 to 9 visual rating indicating the resistance toDiplodia Ear Mold. A higher score indicates a higher resistance.

DRP EAR=DROPPED EARS. A measure of the number of dropped ears per plotand represents the percentage of plants that did not drop ears prior toharvest.

D/T=DROUGHT TOLERANCE. This represents a 1-9 rating for droughttolerance, and is based on data obtained under stress conditions. A highscore indicates good drought tolerance and a low score indicates poordrought tolerance.

EAR HT=EAR HEIGHT. The ear height is a measure from the ground to thehighest placed developed ear node attachment and is measured in inches.

EAR MLD=General Ear Mold. Visual rating (1-9 score) where a "1" is verysusceptible and a "9" is very resistant. This is based on overall ratingfor ear mold of mature ears without determining the specific moldorganism, and may not be predictive for a specific ear mold.

EAR SZ=EAR SIZE. A 1 to 9 visual rating of ear size. The higher therating the larger the ear size.

ECB 1LF=EUROPEAN CORN BORER FIRST GENERATION LEAF FEEDING (Ostrinianubilalis). A 1 to 9 visual rating indicating the resistance topreflowering leaf feeding by first generation European Corn Borer. Ahigher score indicates a higher resistance.

ECB 2IT=EUROPEAN CORN BORER SECOND GENERATION INCHES OF TUNNELING(Ostrinia nubilalis). Average inches of tunneling per plant in thestalk.

ECB 2SC=EUROPEAN CORN BORER SECOND GENERATION (Ostrinia nubilalis). A 1to 9 visual rating indicating post flowering degree of stalk breakageand other evidence of feeding by European Corn Borer, Second Generation.A higher score indicates a higher resistance.

ECB DPE=EUROPEAN CORN BORER DROPPED EARS (Ostrinia nubilalis). Droppedears due to European Corn Borer. Percentage of plants that did not dropears under second generation corn borer infestation.

EST CNT=EARLY STAND COUNT. This is a measure of the stand establishmentin the spring and represents the number of plants that emerge on perplot basis for the inbred or hybrid.

EYE SPT=Eye Spot (Kabatiella zeae or Aureobasidium zeae). A 1 to 9visual rating indicating the resistance to Eye Spot. A higher scoreindicates a higher resistance.

FUS ERS=FUSARIUM EAR ROT SCORE (Fusarium moniliforme or Fusariumsubglutinans). A 1 to 9 visual rating indicating the resistance toFusarium ear rot. A higher score indicates a higher resistance.

GDU=Growing Degree Units. Using the Barger Heat Unit Theory, whichassumes that maize growth occurs in the temperature range 50° F.-86° F.and that temperatures outside this range slow down growth; the maximumdaily heat unit accumulation is 36 and the minimum daily heat unitaccumulation is 0. The seasonal accumulation of GDU is a major factor indetermining maturity zones.

GDU SHD=GDU TO SHED. The number of growing degree units (GDUs) or heatunits required for an inbred line or hybrid to have approximately 50percent of the plants shedding pollen and is measured from the time ofplanting. Growing degree units are calculated by the Barger Method,where the heat units for a 24-hour period are: ##EQU1##

The highest maximum temperature used is 86° F. and the lowest minimumtemperature used is 50° F. For each inbred or hybrid it takes a certainnumber of GDUs to reach various stages of plant development.

GDU SLK=GDU TO SILK. The number of growing degree units required for aninbred line or hybrid to have approximately 50 percent of the plantswith silk emergence from time of planting. Growing degree units arecalculated by the Barger Method as given in GDU SHD definition.

GIB ERS=GIBBERELLA EAR ROT (PINK MOLD) (Gibberella zeae). A 1 to 9visual rating indicating the resistance to Gibberella Ear Rot. A higherscore indicates a higher resistance.

GLF SPT=Gray Leaf Spot (Cercospora zeae-maydis). A 1 to 9 visual ratingindicating the resistance to Gray Leaf Spot. A higher score indicates ahigher resistance.

GOS WLT=Goss' Wilt (Corynebacterium nebraskense). A 1 to 9 visual ratingindicating the resistance to Goss' Wilt. A higher score indicates ahigher resistance.

GRN APP=GRAIN APPEARANCE. This is a 1 to 9 rating for the generalappearance of the shelled grain as it is harvested based on such factorsas the color of harvested grain, any mold on the grain, and any crackedgrain. High scores indicate good grain quality.

H/POP=YIELD AT HIGH DENSITY. Yield ability at relatively high plantdensities on 1-9 relative rating system with a higher number indicatingthe hybrid responds well to high plant densities for yield relative toother hybrids. A 1, 5, and 9 would represent very poor, average, andvery good yield response, respectively, to increased plant density.

HC BLT=HELMINTHOSPORIUM CARBONUM LEAF BLIGHT (Helminthosporiumcarbonum). A 1 to 9 visual rating indicating the resistance toHelminthosporium infection. A higher score indicates a higherresistance.

HD SMT=HEAD SMUT (Sphacelotheca reiliana). This score indicates thepercentage of plants not infected.

INC D/A=GROSS INCOME (DOLLARS PER ACRE). Relative income per acreassuming drying costs of two cents per point above 15.5 percent harvestmoisture and current market price per bushel.

INCOME/ACRE. Income advantage of hybrid to be patented over other hybridon per acre basis.

INC ADV=GROSS INCOME ADVANTAGE. GROSS INCOME advantage of variety #1over variety #2.

L/POP=YIELD AT LOW DENSITY. Yield ability at relatively low plantdensities on a 1-9 relative system with a higher number indicating thehybrid responds well to low plant densities for yield relative to otherhybrids. A 1, 5, and 9 would represent very poor, average, and very goodyield response, respectively, to low plant density.

MDM CPX=MAIZE DWARF MOSAIC COMPLEX (MDMV=Maize Dwarf Mosaic Virus andMCDV=Maize Chlorotic Dwarf Virus). A 1 to 9 visual rating indicating theresistance to Maize Dwarf Mosaic Complex. A higher score indicates ahigher resistance.

MST=HARVEST MOISTURE. The moisture is the actual percentage moisture ofthe grain at harvest.

MST ADV=MOISTURE ADVANTAGE. The moisture advantage of variety #1 overvariety #2 as calculated by: MOISTURE of variety #2--MOISTURE of variety#1=MOISTURE ADVANTAGE of variety #1.

NLF BLT=Northern Leaf Blight (Helminthosporium turcicum or Exserohilumturcicum). A 1 to 9 visual rating indicating the resistance to NorthernLeaf Blight. A higher score indicates a higher resistance.

PLT HT=PLANT HEIGHT. This is a measure of the height of the plant fromthe ground to the tip of the tassel in inches.

POL SC=POLLEN SCORE. A 1 to 9 visual rating indicating the amount ofpollen shed. The higher the score the more pollen shed.

POL WT=POLLEN WEIGHT. This is calculated by dry weight of tasselscollected as shedding commences minus dry weight from similar tasselsharvested after shedding is complete.

It should be understood that the inbred can, through routinemanipulation of cytoplasmic or other factors, be produced in amale-sterile form. Such embodiments are also contemplated within thescope of the present claims.

POP K/A=PLANT POPULATIONS. Measured as 1000s per acre.

POP ADV=PLANT POPULATION ADVANTAGE. The plant population advantage ofvariety #1 over variety #2 as calculated by PLANT POPULATION of variety#2--PLANT POPULATION of variety #1=PLANT POPULATION ADVANTAGE of variety#1.

PRM=PREDICTED RELATIVE MATURITY. This trait, predicted relativematurity, is based on the harvest moisture of the grain. The relativematurity rating is based on a known set of checks and utilizes standardlinear regression analyses and is also referred to as the ComparativeRelative Maturity Rating System that is similar to the MinnesotaRelative Maturity Rating System.

PRM SHD=A relative measure of the growing degree units (GDU) required toreach 50% pollen shed. Relative values are predicted values from thelinear regression of observed GDU's on relative maturity of commercialchecks.

RT LDG=ROOT LODGING. Root lodging is the percentage of plants that donot root lodge; plants that lean from the vertical axis at anapproximately 30° angle or greater would be counted as root lodged.

RTL ADV=ROOT LODGING ADVANTAGE. The root lodging advantage of variety #1over variety #2.

SCT GRN=SCATTER GRAIN. A 1 to 9 visual rating indicating the amount ofscatter grain (lack of pollination or kernel abortion) on the ear. Thehigher the score the less scatter grain.

SDG VGR=SEEDLING VIGOR. This is the visual rating (1 to 9) of the amountof vegetative growth after emergence at the seedling stage(approximately five leaves). A higher score indicates better vigor.

SEL IND=SELECTION INDEX. The selection index gives a single measure ofthe hybrid's worth based on information for up to five traits. A maizebreeder may utilize his or her own set of traits for the selectionindex. One of the traits that is almost always included is yield. Theselection index data presented in the tables represent the mean valueaveraged across testing stations.

SLF BLT=SOUTHERN LEAF BLIGHT (Helminthosporium maydis or Bipolarismaydis). A 1 to 9 visual rating indicating the resistance to SouthernLeaf Blight. A higher score indicates a higher resistance.

SOU RST=SOUTHERN RUST (Puccinia polysora). A 1 to 9 visual ratingindicating the resistance to Southern Rust. A higher score indicates ahigher resistance.

STA GRN=STAY GREEN. Stay green is the measure of plant health near thetime of black layer formation (physiological maturity). A high scoreindicates better late-season plant health.

STD ADV=STALK STANDING ADVANTAGE. The advantage of variety #1 overvariety #2 for the trait STK CNT.

STK CNT=NUMBER OF PLANTS. This is the final stand or number of plantsper plot.

STK LDG=STALK LODGING. This is the percentage of plants that did notstalk lodge (stalk breakage) as measured by either natural lodging orpushing the stalks and determining the percentage of plants that breakbelow the ear.

STW WLT=Stewart's Wilt (Erwinia stewartii). A 1 to 9 visual ratingindicating the resistance to Stewart's Wilt. A higher score indicates ahigher resistance.

TAS BLS=TASSEL BLAST. A 1 to 9 visual rating was used to measure thedegree of blasting (necrosis due to heat stress) of the tassel at thetime of flowering. A would indicate a very high level of blasting attime of flowering, while a 9 would have no tassel blasting.

TAS SZ=TASSEL SIZE. A 1 to 9 visual rating was used to indicate therelative size of the tassel. The higher the rating the larger thetassel.

TAS WT=TASSEL WEIGHT. This is the average weight of a tassel (grams)just prior to pollen shed.

TEX EAR=EAR TEXTURE. A 1 to 9 visual rating was used to indicate therelative hardness (smoothness of crown) of mature grain. A 1 would bevery soft (extreme dent) while a 9 would be very hard (flinty or verysmooth crown).

TILLER=TILLERS. A count of the number of tillers per plot that couldpossibly shed pollen was taken. Data is given as a percentage oftillers: number of tillers per plot divided by number of plants perplot.

TST WT=TEST WEIGHT (UNADJUSTED). The measure of the weight of the grainin pounds for a given volume (bushel).

TST WTA=TEST WEIGHT ADJUSTED. The measure of the weight of the grain inpounds for a given volume (bushel) adjusted for 15.5 percent moisture.

TSW ADV=TEST WEIGHT ADVANTAGE. The test weight advantage of variety overvariety #2.

WIN M %=PERCENT MOISTURE WINS.

WIN Y %=PERCENT YIELD WINS.

YLD=YIELD. It is the same as BU ACR ABS.

YLD ADV=YIELD ADVANTAGE. The yield advantage of variety #1 over variety#2 as calculated by: YIELD of variety #1--YIELD variety #2=yieldadvantage of variety #1.

YLD SC=YIELD SCORE. A 1 to 9 visual rating was used to give a relativerating for yield based on plot ear piles. The higher the rating thegreater visual yield appearance.

DETAILED DESCRIPTION OF THE INVENTION

Inbred maize lines are typically developed for use in the production ofhybrid maize lines. Inbred maize lines need to be highly homogeneous,homozygous and reproducible to be useful as parents of commercialhybrids. There are many analytical methods available to determine thehomozygotic and phenotypic stability of these inbred lines.

The oldest and most traditional method of analysis is the observation ofphenotypic traits. The data is usually collected in field experimentsover the life of the maize plants to be examined. Phenotypiccharacteristics most often observed are for traits associated with plantmorphology, ear and kernel morphology, insect and disease resistance,maturity, and yield.

In addition to phenotypic observations, the genotype of a plant can alsobe examined. There are many laboratory-based techniques available forthe analysis, comparison and characterization of plant genotype; amongthese are Isozyme Electrophoresis, Restriction Fragment LengthPolymorphisms (RFLPs), Randomly Amplified Polymorphic DNAs (RAPDs),Arbitrarily Primed Polymerase Chain Reaction (AP-PCR), DNA AmplificationFingerprinting (DAF), Sequence Characterized Amplified Regions (SCARs),Amplified Fragment Length Polymorphisms (AFLPs), and Simple SequenceRepeats (SSRs) which are also referred to as Microsatellites.

The most widely used of these laboratory techniques are IsozymeElectrophoresis and RFLPs as discussed in Lee, M., "Inbred Lines ofMaize and Their Molecular Markers," The Maize Handbook,(Springer-Verlag, New York, Inc. 1994, at 423-432) incorporated hereinby reference. Isozyme Electrophoresis is a useful tool in determininggenetic composition, although it has relatively low number of availablemarkers and the low number of allelic variants among maize inbreds.RFLPs have the advantage of revealing an exceptionally high degree ofallelic variation in maize and the number of available markers is almostlimitless.

Maize RFLP linkage maps have been rapidly constructed and widelyimplemented in genetic studies. One such study is described inBoppenmaier, et al., "Comparisons among strains of inbreds for RFLPs",Maize Genetics Cooperative Newsletter, 65:1991, pg. 90, is incorporatedherein by reference. This study used 101 RFLP markers to analyze thepatterns of 2 to 3 different deposits each of five different inbredlines. The inbred lines had been selfed from 9 to 12 times before beingadopted into 2 to 3 different breeding programs. It was results fromthese 2 to 3 different breeding programs that supplied the differentdeposits for analysis. These five lines were maintained in the separatebreeding programs by selfing or sibbing and rogueing off-type plants foran additional one to eight generations. After the RFLP analysis wascompleted, it was determined the five lines showed 0-2% residualheterozygosity. Although this was a relatively small study, it can beseen using RFLPs that the lines had been highly homozygous prior to theseparate strain maintenance.

Inbred maize line PH42B is a yellow, dent maize inbred that is bestsuited as a female in crosses for producing first generation F₁ maizehybrids. Inbred maize line PH42B is best adapted to the Central CornBelt and the Northcentral and Northeast regions of the United States andcan be used to produce hybrids from approximately 108 relative maturitybased on the Comparative Relative Maturity Rating System for harvestmoisture of grain. Inbred maize line PH42B, as an inbred per se, yieldswell for its maturity, has a favorable kernel size for planting, and hasalmost no tillers. In hybrid combination, PH42B demonstrates high grainyield and dries fast in the field. PH42B hybrids also demonstrateexcellent staygreen.

The inbred has shown uniformity and stability within the limits ofenvironmental influence for all the traits as described in the VarietyDescription Information (Table 1) that follows. The inbred has beenself-pollinated and ear-rowed a sufficient number of generations withcareful attention paid to uniformity of plant type to ensure thehomozygosity and phenotypic stability necessary to use in commercialproduction. The line has been increased both by hand and in isolatedfields with continued observation for uniformity. No variant traits havebeen observed or are expected in PH42B.

Inbred maize line PH42B, being substantially homozygous, can bereproduced by planting seeds of the line, growing the resulting maizeplants under self-pollinating or sib-pollinating conditions withadequate isolation, and harvesting the resulting seed, using techniquesfamiliar to the agricultural arts.

                  TABLE 1                                                         ______________________________________                                        VARIETY DESCRIPTION INFORMATION                                               INBRED = PH42B                                                                ______________________________________                                            Type: Dent                                                                A.  Maturity: Average cross maturity zones. Zone: 0                               GDU Shed: 1430                                                                GDU Silk: 1440                                                                No. Reps: 47                                                              B.  Plant Characteristics:                                                        Length of top ear internode: 16 cm                                            Number of ears per stalk: Single Plant Height: 224.5 cm.                      Ear height (to base of top ear): 79 cm                                        Number of tillers: None                                                       Cytoplasm type: Normal                                                    C.  Leaf:                                                                         Color: (B14) Dark Green*                                                      Angle from Stalk: 30-60 degrees                                               Marginal Waves: (WF9) Few                                                     Number of Leaves (mature plants): 21                                          Sheath Pubescence: (W22) Light                                                Longitudinal Creases: (PA11) Many                                             Length (Ear node leaf): 86 cm                                                 Width (widest point, ear node leaf): 10 cm                                D.  Tassel:                                                                       Number lateral branches: 1                                                    Peduncle Length (top leaf to basal branches): 24 cm                           Anther Color: Yellow*                                                         Glume Color: Green*                                                       E.  Ear (Husked Ear Data Except When Stated Otherwise):                           Length: 18 cm                                                                 Weight: 141 gm                                                                Mid-point Diameter: 44 mm                                                     Silk Color: Green*                                                            Husk Extension (Harvest stage): Medium (Barely Covering                       Ear)                                                                          Husk Leaf: Long (>15 cm)                                                      Taper of Ear: Average                                                         Position of Shank (dry husks): Upright                                        Kernel Rows: Distinct, Slightly curved Number=16                              Husk Color (fresh): Light green*                                              Husk Color (dry): Buff*                                                       Shank Length: 19 cm                                                           Shank (No. of internodes): 11                                             F.  Kernel (Dried):                                                               Size (from ear mid-point)                                                     Length: 11 mm                                                                 Width: 8 mm                                                                   Thick: 5 mm                                                                   Shape Grade (% rounds) (31% medium round) 20-40                               Pericarp Color: Colorless*                                                    Aleurone Color: Homozygous Yellow*                                            Endosperm Color: Yellow*                                                      Endosperm Type: Normal Starch                                                 Gm Wt/100 Seeds (unsized): 31 gm                                          G.  Cob:                                                                          Diameter at mid-point: 25 mm                                                  Strength: Strong                                                              Color: Red*                                                               H.  Diseases:                                                                     Corn Lethal Necrosis (MCMV=Maize Chlorotic Mottle                             Virus and MDMV=Maize                                                          Dwarf Mosaic Virus): Intermediate                                             S. Leaf Blight (B. maydis): Intermediate                                      N. Leaf Blight (E. turcicum): Highly Resistant                                Common Rust (P. sorghi): Resistant                                            Eye Spot (K. zeae): Resistant                                                 Gray Leaf Spot (C. zeae): Intermediate                                        Fusarium Ear Mold (F. moniliforme): Susceptible                           I.  Insects:                                                                      European Corn Borer-1 Leaf Damage (Preflowering):                             Intermediate                                                                  European Corn Borer-2 (Post-flowering): Intermediate                          The above descriptions are based on a scale of 1-9, 1 being                   highly susceptible, 9 being highly resistant.                                 S (Susceptible): Would generally represent a score of 1-3.                    I (Intermediate): Would generally represent a score of 4-5.                   R (Resistant): Would generally represent a score of 6-7.                      H (Highly Resistant) Would generally represent a score of                     8-9. Highly resistant does not imply the inbred is immune.                J.  Varieties Most Closely Resembling: PHT11 and PHP38                        ______________________________________                                         *In interpreting the foregoing color designations, reference may be had t     the Munsell Glossy Book of Color, a standard color reference.                 Data for Items B, C, D, E, F, and G is based primarily on a maximum of 2      reps from Johnston, Iowa grown in 1994, plus description information from     the maintaining station.                                                 

INDUSTRIAL APPLICABILITY

This invention also is directed to methods for producing a maize plantby crossing a first parent maize plant with a second parent maize plantwherein the first or second parent maize plant is an inbred maize plantof the line PH42B. Further, both first and second parent maize plantscan come from the inbred maize line PH42B. Thus, any such methods usingthe inbred maize line PH42B are part of this invention: selfing,backcrosses, hybrid production, crosses to populations, and the like.All plants produced using inbred maize line PH42B as a parent are withinthe scope of this invention. Advantageously, the inbred maize line isused in crosses with other, different, maize inbreds to produce firstgeneration (F₁) maize hybrid seeds and plants with superiorcharacteristics.

As used herein, the term plant includes plant cells, plant protoplasts,plant cell tissue cultures from which maize plants can be regenerated,plant calli, plant clumps, and plant cells that are intact in plants orparts of plants, such as embryos, pollen, ovules, flowers, kernels,ears, cobs, leaves, husks, stalks, roots, root tips, anthers, silk andthe like.

Duncan, Williams, Zehr, and Widholm, Planta (1985) 165:322-332 reflectsthat 97% of the plants cultured that produced callus were capable ofplant regeneration. Subsequent experiments with both inbreds and hybridsproduced 91% regenerable callus that produced plants. In a further studyin 1988; Songstad, Duncan & Widholm in Plant Cell Reports (1988),7:262-265 reports several media additions that enhance regenerability ofcallus of two inbred lines. Other published reports also indicated that"nontraditional" tissues are capable of producing somatic embryogenesisand plant regeneration. K. P. Rao, et al., Maize Genetics CooperationNewsletter, 60:64-65 (1986), refers to somatic embryogenesis from glumecallus cultures and B. V. Conger, et al., Plant Ceil Reports, 6:345-347(1987) indicates somatic embryogenesis from the tissue cultures of maizeleaf segments. Thus, it is clear from the literature that the state ofthe art is such that these methods of obtaining plants are, and were,"conventional" in the sense that they are routinely used and have a veryhigh rate of success.

Tissue culture of maize is described in European Patent Application,publication 160,390, incorporated herein by reference. Maize tissueculture procedures are also described in Green and Rhodes, "PlantRegeneration in Tissue Culture of Maize," Maize for Biological Research(Plant Molecular Biology Association, Charlottesville, Va. 1982, at367-372) and in Duncan, et al., "The Production of Callus Capable ofPlant Regeneration from Immature Embryos of Numerous Zea MaysGenotypes," 165 Planta 322-332 (1985). Thus, another aspect of thisinvention is to provide cells which upon growth and differentiationproduce maize plants having the physiological and morphologicalcharacteristics of inbred line PH42B.

Maize is used as human food, livestock feed, and as raw material inindustry. The food uses of maize, in addition to human consumption ofmaize kernels, include both products of dry- and wet-milling industries.The principal products of maize dry milling are grits, meal and flour.The maize wet-milling industry can provide maize starch, maize syrups,and dextrose for food use. Maize oil is recovered from maize germ, whichis a by-product of both dry- and wet-milling industries.

Maize, including both grain and non-grain portions of the plant, is alsoused extensively as livestock feed, primarily for beef cattle, dairycattle, hogs, and poultry.

Industrial uses of maize include production of ethanol, maize starch inthe wet-milling industry and maize flour in the dry-milling industry.The industrial applications of maize starch and flour are based onfunctional properties, such as viscosity, film formation, adhesiveproperties, and ability to suspend particles. The maize starch and flourhave application in the paper and textile industries. Other industrialuses include applications in adhesives, building materials, foundrybinders, laundry starches, explosives, oil-well muds, and other miningapplications.

Plant parts other than the grain of maize are also used in industry: forexample, stalks and husks are made into paper and wallboard and cobs areused for fuel and to make charcoal.

The seed of inbred maize line PH42B, the plant produced from the inbredseed, the hybrid maize plant produced from the crossing of the inbred,hybrid seed, and various parts of the hybrid maize plant can be utilizedfor human food, livestock feed, and as a raw material in industry.

PERFORMANCE EXAMPLES OF PH42B

In the examples that follow, the traits and characteristics of inbredmaize line PH42B are presented as an inbred per se and in hybridcombination. The data collected on inbred maize line PH42B is presentedfor key characteristics and traits.

The inbred per se results in Table 2A compare PH42B to PHP38, a closecomparison line for this maturity. The results show PH42B issignificantly higher yielding than PHP38. In addition, PH42B has asignificantly lower harvest moisture than PHP38. Inbred PH42B alsodemonstrates a better staygreen score than that of PHP38.

Table 2B compares PH42B to its parent, PHT11. The inbred per se resultsshow PH42B is significantly higher yielding than PHT11. In addition,PH42B has a significantly higher staygreen score than PHT11.

Table 3A compares the general combining abilities of PH42B and PHP38.The PH42B hybrids are higher yielding with a lower harvest moisture thanthe PHP38 hybrids. Both PH42B and PHP38 hybrids demonstrate goodstaygreen scores.

The general combining ability results in Table 3B compare PH42B to PHT11in hybrid combination. The PH42B hybrids are higher yielding withsignificantly higher staygreen scores than the PHT11 hybrids. Both PH42Band PHT11 have lower harvest moisture levels.

Table 4A compares the specific combining abilities of PH42B and PHP38 inhybrid combination with PHN46. Both hybrids have similar high yields,however, the PH42B hybrid has significantly lower harvest moisture. Bothhybrids demonstrate very good staygreen.

Table 4B compares the specific combining abilities of PH42B and PHT11 inhybrid combination with PHN46. The PH42B hybrid demonstrates a highyield that is somewhat higher than the PHT11 hybrid. Although the PHT11hybrid has a lower harvest moisture, both hybrids are below the mean.The PH42B hybrid has a far superior staygreen score that isstatistically significant at the 99% probability level.

                                      TABLE 2A                                    __________________________________________________________________________    PAIRED INBRED COMPARISON DATA                                                 VARIETY #1 = PH42B                                                            VARIETY #2 = PHP38                                                            __________________________________________________________________________                BU  BU  MST TST SDG EST TIL GDU GDU                                       VAR ACR ACR     WT  VGR CNT LER SHD SLK                                       #   ABS % MN                                                                              ABS ABS ABS ABS ABS ABS ABS                               __________________________________________________________________________    TOTAL SUM                                                                             1   102.1                                                                             122 17.3                                                                              57.1                                                                              5.5 28.3                                                                              0.8 143,1                                                                             144,2                                     2   77.8                                                                              94  19.0                                                                              59.1                                                                              6.2 27.2                                                                              1.4 145,6                                                                             146,8                                     LOCS                                                                              11  11  16  11  43  63  40  56  56                                        REPS                                                                              22  22  27  22  51  88  50  60  60                                        DIFF                                                                              24.3                                                                              28  1.8 1.9 0.7 1.1 0.6 2.4 2.6                                       PROB                                                                              .000#                                                                             .000#                                                                             .003#                                                                             .031+                                                                             .001#                                                                             .043+                                                                             .133                                                                              .000#                                                                             .000#                             __________________________________________________________________________                POL TAS PLT EAR RT  STA STK BRT GRN                                       VAR SC  SZ  HT  HT  LDG GRN LDG STK APP                                       #   ABS ABS ABS ABS ABS ABS ABS ABS ABS                               __________________________________________________________________________    TOTAL SUM                                                                             1   2.3 1.8 84.0                                                                              32.8                                                                              82.3                                                                              6.7 97.1                                                                              93.1                                                                              6.2                                       2   5.6 5.3 79.6                                                                              31.9                                                                              100.0                                                                             5.4 98.4                                                                              93.5                                                                              7.8                                       LOCS                                                                              21  25  24  23  6   20  7   10  3                                         REPS                                                                              22  26  31  29  6   28  13  10  6                                         DIFF                                                                              3.3 3.5 4.4 1.0 17.7                                                                              1.3 1.3 0.4 1.6                                       PROB                                                                              .000#                                                                             .000#                                                                             .001#                                                                             .331                                                                              .102                                                                              .012+                                                                             .592                                                                              .903                                                                              .321                              __________________________________________________________________________                SCT EAR TEX EAR BAR DRP GLF SLF STW                                       VAR GRN SZ  EAR MLD PLT EAR SPT BLT WLT                                       #   ABS ABS ABS ABS ABS ABS ABS ABS ABS                               __________________________________________________________________________    TOTAL SUM                                                                             1   6.5 6.4 4.3 6.8 91.6                                                                              100.0                                                                             4.3 4.0 7.0                                       2   6.4 5.3 6.4 7.7 92.2                                                                              99.8                                                                              3.7 6.2 4.0                                       LOCS                                                                              13  11  9   11  36  4   6   2   1                                         REPS                                                                              14  11  9   12  40  8   6   2   1                                         DIFF                                                                              0.2 1.1 2.1 0.9 0.5 0.2 0.6 2.2 3.0                                       PROB                                                                              .753                                                                              .010+                                                                             .001#                                                                             .064*                                                                             .790                                                                              .391                                                                              .396                                                                              .234                                  __________________________________________________________________________                FUS EYE COM ECB ECB                                                       VAR ERS SPT RST 1LF 2SC                                                       #   ABS ABS ABS ABS ABS                                               __________________________________________________________________________    TOTAL SUM                                                                             1   3.3 6.5 5.3 4.7 4.0                                                       2   5.3 5.5 5.7 4.0 5.7                                                       LOCS                                                                              4   2   3   7   3                                                         REPS                                                                              4   2   3   7   4                                                         DIFF                                                                              2.0 1.0 0.3 0.7 1.7                                                       PROB                                                                              .161                                                                              .000#                                                                             .667                                                                              .140                                                                              .300                                              __________________________________________________________________________     * = 10% SIG                                                                   + = 5% SIG                                                                    # = 1% SIG                                                               

                                      TABLE 2B                                    __________________________________________________________________________    PAIRED INBRED COMPARISON DATA                                                 VARIETY #1 = PH42B                                                            VARIETY #2 = PHT11                                                            __________________________________________________________________________                BU  BU  MST TST SDG EST TIL GDU GDU                                       VAR ACR ACR     WT  VGR CNT LER SHD SLK                                       #   ABS % MN                                                                              ABS ABS ABS ABS ABS ABS ABS                               __________________________________________________________________________    TOTAL SUM                                                                             1   97.1                                                                              118 23.0                                                                              54.7                                                                              5.4 35.5                                                                              0.9 142,4                                                                             143,9                                     2   67.6                                                                              82  22.8                                                                              56.8                                                                              6.0 35.0                                                                              1.1 143,9                                                                             144,3                                     LOCS                                                                              28  28  36  28  40  78  50  60  55                                        REPS                                                                              55  55  63  56  52  118 67  69  60                                        DIFF                                                                              30.1                                                                              37  0.2 2.1 0.5 0.5 0.2 1.5 0.4                                       PROB                                                                              .000#                                                                             .000#                                                                             .675                                                                              .000#                                                                             .015+                                                                             .337                                                                              .626                                                                              .000#                                                                             .418                              __________________________________________________________________________                POL TAS PLT EAR RT  STA STK BRT GRN                                       VAR SC  SZ  HT  HT  LDG GRN LDG STK APP                                       #   ABS ABS ABS ABS ABS ABS ABS ABS ABS                               __________________________________________________________________________    TOTAL SUM                                                                             1   2.5 1.6 84.6                                                                              33.8                                                                              79.6                                                                              7.0 97.3                                                                              92.3                                                                              5.6                                       2   2.3 1.6 94.1                                                                              36.8                                                                              67.7                                                                              5.0 90.5                                                                              92.5                                                                              6.6                                       LOCS                                                                              20  21  28  25  9   18  18  9   9                                         REPS                                                                              21  23  42  37  11  28  34  9   18                                        DIFF                                                                              0.1 0.0 9.5 3.0 11.9                                                                              2.0 6.8 0.1 1.0                                       PROB                                                                              .582                                                                              .715                                                                              .000#                                                                             .000#                                                                             .237                                                                              .001#                                                                             .024+                                                                             .968                                                                              .048+                             __________________________________________________________________________                SCT EAR TEX EAR BAR DRP GLF NLF SLF                                       VAR GRN SZ  EAR MLD PLT EAR SPT BLT BLT                                       #   ABS ABS ABS ABS ABS ABS ABS ABS ABS                               __________________________________________________________________________    TOTAL SUM                                                                             1   6.5 6.7 4.5 7.1 93.1                                                                              99.8                                                                              4.3 8.5 4.0                                       2   6.4 4.0 6.8 7.4 89.3                                                                              99.4                                                                              3.2 7.0 3.0                                       LOCS                                                                              11  7   6   10  42  13  5   2   1                                         REPS                                                                              12  7   6   11  49  26  5   2   1                                         DIFF                                                                              0.1 2.7 2.3 0.3 3.8 0.4 1.1 1.5 1.0                                       PROB                                                                              .846                                                                              .013+                                                                             .005#                                                                             .647                                                                              .091*                                                                             .240                                                                              .219                                                                              .500                                  __________________________________________________________________________                FUS EYE COM ECB ECB                                                       VAR ERS SPT RST 1LF 2SC                                                       #   ABS ABS ABS ABS ABS                                               __________________________________________________________________________    TOTAL SUM                                                                             1   4.5 6.5 5.7 4.8 4.4                                                       2   6.0 6.0 3.7 5.2 4.6                                                       LOCS                                                                              2   2   3   6   4                                                         REPS                                                                              2   2   4   6   6                                                         DIFF                                                                              1.5 0.5 2.0 0.3 0.2                                                       PROB                                                                              .500                                                                              .795                                                                              .074*                                                                             .661                                                                              .704                                              __________________________________________________________________________     * = 10% SIG                                                                   + = 5% SIG                                                                    # = 1% SIG                                                               

                                      TABLE 3A                                    __________________________________________________________________________    Average Inbred By Tester Performance Comparing PH42B To PHP38 Crossed To      The Same                                                                      Inbred Testers And Grown In The Same Experiments.                             __________________________________________________________________________                  SEL     BU  BU  PRM     TST SDG EST                                           IND PRM ACR ACR SHD MST WT  VGR CNT                                           % MN                                                                              ABS ABS % MN                                                                              ABS % MN                                                                              ABS % MN                                                                              % MN                            __________________________________________________________________________    TOTAL SUM                                                                             REPLIC.                                                                             20  23  186 186 20  213 115 98  118                                     LOCS  20  23  165 165 20  178 103 76  102                                     PH42B 106 108 176 105 113 93  56  96  99                                      PHP38 103 110 171 102 111 100 56  120 102                                     DIFF  3   2   5   3   2   7   0   24  3                                       PR > T                                                                              0.15                                                                              0.00                                                                              0.01                                                                              0.01                                                                              0.00                                                                              0.00                                                                              0.01                                                                              0.00                                                                              0.04                            __________________________________________________________________________                  GDU GDU STK PLT EAR RT  STA STK BRT                                           SHD SLK CNT HT  HT  LDG GRN LDG STK                                           % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                            __________________________________________________________________________    TOTAL SUM                                                                             REPLIC.                                                                             67  39  239 98  98  78  96  152 33                                      LOCS  51  28  193 86  86  59  84  127 26                                      PH42B 104 102 99  101 105 100 112 100 101                                     PHP38 102 101 101 99  103 104 112 102 100                                     DIFF  1   1   1   2   2   4   0   2   1                                       PR > T                                                                              0.02                                                                              0.30                                                                              0.04                                                                              0.00                                                                              0.02                                                                              0.07                                                                              0.96                                                                              0.05                                                                              0.28                            __________________________________________________________________________                  GRN SLF EYE ECB ECB DRP GLF NLF                                               APP BLT SPT DPE 2SC EAR SPT BLT                                               % MN                                                                              ABS ABS ABS ABS % MN                                                                              ABS ABS                                 __________________________________________________________________________    TOTAL SUM                                                                             REPLIC.                                                                             33  13  8   12  13  55  9   1                                           LOCS  33  5   7   12  11  46  9   1                                           PH42B 102 4   5   99  6   100 4   8                                           PHP38 100 5   4   99  5   100 2   8                                           DIFF  1   1   1   0   0   0   1   0                                           PR > T                                                                              0.65                                                                              0.00                                                                              0.09                                                                              0.59                                                                              0.54                                                                              0.89                                                                              0.05                                    __________________________________________________________________________     *PR > T values are valid only for comparisons with Locs >= 10.           

                                      TABLE 3B                                    __________________________________________________________________________    Average Inbred By Tester Performance Comparing PH42B To PHT11 Crossed To      The Same                                                                      Inbred Testers And Grown In The Same Experiments.                             __________________________________________________________________________                  SEL     BU  BU  PRM     TST SDG EST                                           IND PRM ACR ACR SHD MST WT  VGR CNT                                           % MN                                                                              ABS ABS % MN                                                                              ABS % MN                                                                              ABS % MN                                                                              % MN                            __________________________________________________________________________    TOTAL SUM                                                                             REPLIC.                                                                             16  19  172 172 17  192 111 88  113                                     LOCS  16  19  155 155 17  165 101 69  99                                      PH42B 106 107 177 105 113 94  55  95  99                                      PHT11 100 106 169 100 111 94  56  110 103                                     DIFF  6   1   8   5   1   0   1   16  5                                       PR > T                                                                              0.05                                                                              0.05                                                                              0.00                                                                              0.00                                                                              0.04                                                                              0.73                                                                              0.00                                                                              0.00                                                                              0.00                            __________________________________________________________________________                  GDU GDU STK PLT EAR RT  STA STK BRT                                           SHD SLK CNT HT  HT  LDG GRN LDG STK                                           % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                            __________________________________________________________________________    TOTAL SUM                                                                             REPLIC.                                                                             60  35  218 86  86  72  80  135 24                                      LOCS  46  26  179 77  77  55  72  115 19                                      PH42B 104 102 100 101 105 101 115 100 102                                     PHT11 102 101 101 103 108 103 104 99  102                                     DIFF  2   2   2   2   2   2   11  1   0                                       PR > T                                                                              0.00                                                                              0.00                                                                              0.02                                                                              0.00                                                                              0.04                                                                              0.59                                                                              0.01                                                                              0.25                                                                              0.91                            __________________________________________________________________________                  GRN SLF EYE ECB ECB DRP GLF NLF                                               APP BLT SPT DPE 2SC EAR SPT BLT                                               % MN                                                                              ABS ABS ABS ABS % MN                                                                              ABS ABS                                 __________________________________________________________________________    TOTAL SUM                                                                             REPLIC.                                                                             43  13  9   11  7   60  5   1                                           LOCS  10  5   8   11  7   50  5   1                                           PH42B 95  4   5   99  6   100 3   8                                           PHT11 102 4   5   99  5   100 3   8                                           DIFF  7   0   0   0   1   0   0   0                                           PR > T                                                                              0.01                                                                              0.65                                                                              0.27                                                                              0.78                                                                              0.49                                                                              0.97                                                                              0.37                                    __________________________________________________________________________     *PR > T values are valid only for comparisons with Locs >= 10.           

                                      TABLE 4A                                    __________________________________________________________________________    PAIRED COMPARISON REPORT                                                      VARIETY #1 = PH42B/PHN46                                                      VARIETY #2 = PHP38/PHN46                                                      __________________________________________________________________________                PRM PRM BU  BU  MST TST SDG EST                                           VAR     SHD ACR ACR     WT  CGR CNT                                           #           ABS % MN                                                                              % MN                                                                              ABS % MN                                                                              % MN                                  __________________________________________________________________________    TOTAL SUM                                                                             1   107 113 175.4                                                                             102 96  55.5                                                                              95  100                                           2   109 111 174.0                                                                             101 100 56.4                                                                              122 103                                           LOCS                                                                              30  27  129 129 129 81  59  89                                            REPS                                                                              30  27  148 148 150 92  72  105                                           DIFF                                                                              1   2   1.4 1   4   0.9 27  3                                             PROB                                                                              .000#                                                                             .001#                                                                             .401                                                                              .262                                                                              .000#                                                                             .000#                                                                             .000#                                                                             .026+                                 __________________________________________________________________________                GDU GDU STK PLT EAR RT  STA STK                                           VAR SHD SLK CNT HT  HT  LDG GRN LDG                                           #   % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                  __________________________________________________________________________    TOTAL SUM                                                                             1   103 102 100 100 104 100 116 99                                            2   102 102 102 99  104 104 115 101                                           LOCS                                                                              35  20  134 69  69  41  65  95                                            REPS                                                                              43  25  159 80  80  52  74  112                                           DIFF                                                                              1   0   2   1   1   4   2   2                                             PROB                                                                              .008#                                                                             .803                                                                              .020+                                                                             .042+                                                                             .564                                                                              .183.                                                                             .668                                                                              .095*                                 __________________________________________________________________________                BRT GRN DRP GLF NLF EYE ECB ECB                                           VAR STK APP EAR SPT BLT SPT DPE 2SC                                           #   % MN                                                                              % MN                                                                              % MN                                                                              ABS ABS ABS ABS ABS                                   __________________________________________________________________________    TOTAL SUM                                                                             1   103 99  100 3.0 8.0 4.7 99.3                                                                              6.0                                           2   99  101 100 2.8 8.0 4.1 98.7                                                                              5.3                                           LOCS                                                                              20  24  41  4   1   6   11  7                                             REPS                                                                              25  24  49  4   1   7   11  7                                             DIFF                                                                              4   2   0   0.3 0.0 0.6 0.5 0.7                                           PROB                                                                              .172                                                                              .445                                                                              .624                                                                              .761    .180                                                                              .377                                                                              .426                                  __________________________________________________________________________     * = 10% SIG                                                                   + = 5% SIG                                                                    # = 1% SIG                                                               

                                      TABLE 4B                                    __________________________________________________________________________    PAIRED COMPARISON REPORT                                                      VARIETY #1 = PH42B/PHN46                                                      VARIETY #2 = PHT11/PHN46                                                      __________________________________________________________________________                PRM PRM BU  BU  MST TST SDG EST                                           VAR     SHD ACR ACR     WT  VGR CNT                                           #           ABS % MN                                                                              % MN                                                                              ABS % MN                                                                              % MN                                  __________________________________________________________________________    TOTAL SUM                                                                             1   107 113 173.6                                                                             102 98  54.3                                                                              94  100                                           2   106 111 171.4                                                                             100 95  55.4                                                                              111 105                                           LOCS                                                                              29  26  126 126 126 78  53  84                                            REPS                                                                              29  26  143 143 145 88  64  98                                            DIFF                                                                              1   1   2.2 2   3   1.1 17  5                                             PROB                                                                              .000#                                                                             .010+                                                                             .191                                                                              .069*                                                                             .000#                                                                             .000#                                                                             .000#                                                                             .000#                                 __________________________________________________________________________                GDU GDU STK PLT EAR RT  STA STK                                           VAR SHD SLK CNT HT  HT  LDG GRN LDG                                           #   % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                                                              % MN                                  __________________________________________________________________________    TOTAL SUM                                                                             1   104 102 100 100 105 100 120 99                                            2   103 101 103 103 108 101 108 99                                            LOCS                                                                              35  17  133 65  65  42  57  92                                            REPS                                                                              42  20  157 74  74  53  65  108                                           DIFF                                                                              1   1   3   2   3   1   12  0                                             PROB                                                                              .006#                                                                             .094*                                                                             .000#                                                                             .000#                                                                             .005#                                                                             .832                                                                              .005#                                                                             .666                                  __________________________________________________________________________                BRT GRN DRP GLF NLF EYE ECB ECB                                           VAR STK APP EAR SPT BLT SPT DPE 2SC                                           #   % MN                                                                              % MN                                                                              % MN                                                                              ABS ABS ABS ABS ABS                                   __________________________________________________________________________    TOTAL SUM                                                                             1   103 94  100 3.0 8.0 4.7 99.3                                                                              6.0                                           2   102 103 100 2.5 8.0 4.4 99.5                                                                              5.0                                           LOCS                                                                              18  35  49  4   1   6   11  7                                             REPS                                                                              23  38  59  4   1   7   11  7                                             DIFF                                                                              0   9   0   0.5 0.0 0.3 0.2 1.0                                           PROB                                                                              .780                                                                              .001#                                                                             .981                                                                              .182    .562                                                                              .765                                                                              .395                                  __________________________________________________________________________     * = 10% SIG                                                                   + = 5% SIG                                                                    # = 1% SIG                                                               

Deposits

Applicant has made a deposit of at least 2500 seeds of Inbred Corn LinePH42B with the American Type Culture Collection (ATCC), Rockville, Md.20852 U.S.A., ATCC Deposit No. 97647. The seeds deposited with the ATCCon Jul. 8, 1996 were taken from the deposit maintained by PioneerHi-Bred International, Inc., 700 Capital Square, 400 Locust Street, DesMoines, Iowa 50309-2340 since prior to the filing date of thisapplication. This deposit of the Inbred Corn Line PH42B will bemaintained in the ATCC depository, which is a public depository, for aperiod of 30 years, or 5 years after the most recent request, or for theenforceable life of the patent, whichever is longer, and will bereplaced if it becomes nonviable during that period. Additionally,Applicant has satisfied all the requirements of 37 C.F.R. §§1.801-1.809,including providing an indication of the viability of the sample.Applicant imposes no restrictions on the availability of the depositedmaterial from the ATCC; however, Applicant has no authority to waive anyrestrictions imposed by law on the transfer of biological material orits transportation in commerce. Applicant does not waive anyinfringement of its rights granted under this patent or under the PlantVariety Protection Act (7 USC 2321 et seq.). Applicant has applied forU.S. Plant Variety Protection of PH42B under Application No. 9600201.

The foregoing invention has been described in detail by way ofillustration and example for purposes of clarity and understanding.However, it will be obvious that certain changes and modifications suchas single gene modifications and mutations, somoclonal variants, variantindividuals selected from large populations of the plants of the instantinbred and the like may be practiced within the scope of the invention,as limited only by the scope of the appended claims.

What is claimed is:
 1. Seed of maize inbred line designated PH42B andhaving ATCC Accession No.
 97647. 2. A maize plant and its parts producedby the seed of claim 1 and its plant parts.
 3. Pollen of the plant ofclaim
 2. 4. An ovule of the plant of claim
 2. 5. A maize plant havingall the physiological and morphological characteristics of the maizeplant named PH42B, the seed of which have been deposited under ATCCAccession No.
 97647. 6. A male sterile maize plant otherwise having allthe physiological and morphological characteristics of the maize plantnamed PH42B, the seed of which have been deposited under ATCC AccessionNo.
 97647. 7. A tissue culture of regenerable cells of an inbred maizeplant PH42B, the seed of which have been deposited under ATCC AccessionNo. 97647, wherein the tissue culture regenerates plants capable ofexpressing all the morphological and physiological characteristics ofthe maize plant named PH42B.
 8. The tissue culture of claim 7, thetissue culture selected from the group consisting of leaves, pollen,embryos, roots, root tips, anthers, silks, flowers, kernels, ears, cobs,husks, stalks, cells and protoplasts thereof.
 9. A maize plantregenerated from the tissue culture of claim 7, capable of expressingall the morphological and physiological characteristics of inbred PH42B,the seed of which have been deposited under ATCC Accession No. 97647.10. A method for producing first generation (F₁) hybrid maize seedcomprising crossing a first inbred parent maize plant with a secondinbred parent maize plant and harvesting the resultant first generation(F₁) hybrid maize seed, wherein said first or second parent maize plantis the maize plant of claim
 2. 11. The method of claim 10 wherein inbredmaize plant PH42B, the seed of which have been deposited under ATCCAccession No. 97647, is the female parent.
 12. The method of claim 10wherein inbred maize plant PH42B, the seed of which have been depositedunder ATCC Accession No. 97647, is the male parent.
 13. An F₁ hybridseed grown therefrom produced by crossing an inbred maize plantaccording to claim 2 with another, different maize plant.
 14. An F₁hybrid plant and its parts grown from the seed of claim 13.